Hi everyone, I’ll preface this by saying that I’m primarily a musician, so I have very little experience with Unity. I apologise in advance if this is something I have foolishly overlooked.
I’m currently preparing a package for submission on the Asset Store, consisting of 673MB of .Wav audio files. I have created a new Unity Project file for the purposes of uploading, and import the AssetStoreTools package. I then create a new subfolder within the ‘Assets’ folder, in which I place my audio files.
However, upon hitting ‘submit’, Unity then compresses the package. However, this seems to actually have the effect of increasing the size of the package. The end file size seems to vary between 1.2GB to 1.4GB, which obviously gets my submission rejected.
Is there something I am doing wrong?
Is the Unity package you’re creating within your Unity project? It might be getting packed again, which would account for the filesize.
I’m currently exporting the package to a different location to the Unity project folder, if that’s what you mean.
This problem seems to be unique to audio files. I’ve created some packages with both .Wav and .MP3 files, and they always seem to approximately double in size. If I export a package containing another file type (in this case Photoshop .PSD files), Unity compresses them correctly and reduces the overall file size.
I’ve seen similar results with audio files… my guess is that it compresses them, but it may store multiple versions for different target platforms?
Well, thanks for confirming that at least it’s not just me getting this issue. I don’t have to worry so much about pilot error. 
I guess there’s nothing for it but lowering the bit depth of my .Wav files to 16bit.